I own an '02 Monty Sport 4x4 with 3.5L, 140k miles. Last week while driving on the highway, it abruptly died. There was no warning, no sputter, just dead. I plan on checking the fuel pressure, but when I crank for a few seconds, I can smell raw fuel from the tail pipe. I had it towed home and have not had much time to try to repair it. The day it happened, I added some fuel (just in case) and tried to crank it; it cranks but will not fire. I immediately noticed that the check engine light does not come on at all when I turn the key or crank the engine. There is no spark and an OBDII reader cannot connect to the computer!

This leads me to believe that there is something wrong with the ECM-PCM (or whatever it is called on this vehicle). My plan is to grab one from a junk yard to see if it makes a difference, and if that fixes it, I'll buy a brand new one just to know it's good. I will be looking into all of this in the next few days, but I have a few questions that I hope someone can answer for me to give me a head start in repairing this problem:

1. With the micro-chipped key, will I have to get the original key that came with the junk yard PCM, or will I have to program my current keys to the replacement computer? If done wrong, I can see this proving to render a used PCM useless.

2. Is there a fuse or link that may have gone bad that would cut power to the PCM? I also plan on finding and checking any grounds that may cause this problem.

3. Having no luck in finding a repair manual for under $200, can anyone tell me the location of the PCM? Which leads me to:

4. Is there a place online where I can access (preferably download) the factory service manual?

5. Is there a way to more accurately test the PCM to determine if it is in fact faulty, or is this simply a case of testing everything around it to rule out all other possibilities?

Again, I plan on finding the answers to all of the questions, but if someone here has experience, it may save me a lot of extra work. Thanks in advance for any help!

 

First of all, very sorry you find yourself in a bind like that. It is always unpleasant to not know what causes your vehicle to malfunction. From the symptoms you describe it definitely sounds like something electrical, possibly PCM related. I would not jump at condemning a PCM right away. In order to conclusively say that PCM is bad, you need to eliminate all other possible culprits (by making sure they all can function properly). Sounds like you have fuel (which is PCM controlled). Start by checking for spark, check if cam and crank position sensors signals are OK. It may be PCM after all. What puzzles me is why it would fail out of the blue? I understand if you were welding on the rig or connected jumper cables backwards, but just going out while driving is strange.
You should be able to locate relevant manuals here:
http://www.mitsubishilinks.com/
Good luck with the repairs. Keep us posted as to what you find out.

 

Thanks for the link. I was on that page a few days ago, but I must have missed it.

To be honest, I broke down on the highway and got out to inspect, mostly to make sure there was no fluid dumping out before I tried cranking. A delivery truck changed lanes and kept coming over the line. I got clipped and ended up with some bad bruises and an ankle broken in 5 places. While I'm going to be out of work for a few months, right now I'm having a hard time getting out there on crutches to start testing! So, bear with me and I will eventually get around to solving this problem.

I really want to find the issue to be other than the PCM, preferably something cheaper. I forgot to mention that the check engine light was on for about a month before this incident because of a oxygen sensor heater circuit. It seems pretty improbable that the check engine light burned out at the same moment that the cam/crank sensor went out, and I can't think of anything else to explain the failure to communicate with a code reader. Right now, I'm hoping for a bad wire or loose connection to the PCM.